Systems and methods for ventilation humidification

ABSTRACT

This disclosure describes systems and methods for humidifying ventilator delivered breathing gases. These systems and methods utilize a hollow cone atomizer (e.g., a pressure swirl atomizer) and/or a heating element associated with a heating circuit and/or a heating tube. In some aspect, the systems and methods utilize received flow, temperature, and/or humidity information to determine an amount of water to add to breathing gases to reach a desired humidity of the breathing gases delivered to the patient. In further aspects, the humidification system can serve as a nebulization system for delivering nebulized medicine.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/411,506, filed 14 May 2019, which claims the benefit of U.S.Provisional Application Ser. No. 62/670,957, filed 14 May 2018, andwhich applications are incorporated herein by reference. To the extentappropriate, a claim of priority is made to each of the above-disclosedapplications.

BACKGROUND

Medical ventilator systems have long been used to provide ventilatoryand supplemental oxygen support to patients. These ventilators typicallycomprise a source of pressurized oxygen which is fluidly connected tothe patient through a conduit or tubing. Some ventilators are used withhumidifiers to humidify the gas delivered to the patient to improvepatient adherence and comfort.

SUMMARY

This disclosure describes systems and methods for humidifying ventilatordelivered breathing gas. The disclosure describes a novel humidificationsystem that utilizes an atomizer and a heating element. For example, theatomizer may be a hollow cone atomizer (e.g., such as a pressure swirlatomizer). Traditionally, pressure swirl atomizers are used to injectwater upstream of a turbine of a high performance jet engine to providea temporary boost in thrust as water increases gas density across theturbine. Such pressure swirl atomizers generally comprise more than oneinlet channel into a swirl chamber, as will be described further below.In some aspects, the disclosure describes a novel humidification systemthat utilizes received flow, humidity, and/or temperature information todetermine the amount of water to add to the breathing gas to obtain adesired percentage of relative humidity, as well as regulating atemperature, of the breathing gases delivered to the patient. In furtheraspects, the humidification system can serve as a nebulization systemfor delivering nebulized medicine. In a first example, a water-solublemedicine may be added to the water and the combination of water andmedicine may be atomized and delivered to the breathing gases by theatomizer. In a second example, a second atomizer designed for the fluidcharacteristics of different medicines may be integrated into thehumidifier (or provided as a removable plug-in device to the humidifier)for delivering nebulized medicines into breathing gases.

In an aspect, a method for humidifying ventilator delivered breathinggases is provided. The method includes receiving, at a humidifier,inspiratory flow information about breathing gases upstream of anatomizer of the humidifier and measuring, by the humidifier, humidityinformation for the breathing gases upstream of the atomizer. The methodfurther includes calculating, based on the inspiratory flow informationand the humidity information, an amount of water to add to the breathinggases to reach a desired humidity and delivering, via the atomizer, theamount of water in bursts of atomized water directly into a flow path ofthe breathing gases. Additionally, the method includes vaporizing theatomized water upon contact of the water with a heating tube in the flowpath downstream of the atomizer to form humidified breathing gases anddelivering the humidified breathing gases to a ventilation tubing systemfor delivery to a patient being ventilated by the ventilator.

In another aspect, a humidifier that provides humidification tobreathing gases for ventilating a patient is provided. The humidifierincludes a first sensor that monitors an inspiratory flow of breathinggases upstream of an atomizer of the humidifier and a second sensor thatmonitors humidity information of the breathing gases upstream of theatomizer. The humidifier further includes a processor that calculates,based on the inspiratory flow and the humidity information, an amount ofwater to add to the breathing gases to reach a desired humidity.Additionally, the humidifier includes a controller that commands theatomizer to deliver the amount of water in bursts of atomized waterdirectly into a flow path of the breathing gases and commands a heatingelement to heat a thermally-conductive material in the flow pathdownstream of the atomizer, wherein the atomized water is vaporized uponcontact of the water with the thermally-conductive material to formhumidified breathing gases for delivery to a patient being ventilated bythe ventilator.

In yet another aspect, a humidifier that provides humidification tobreathing gases for ventilating a patient is provided. The humidifierincludes a sensor that monitors humidity information of the breathinggases upstream of the atomizer, a controller that receives aninspiratory flow of the breathing gases upstream of the humidifier, anda processor that calculates, based on the inspiratory flow and thehumidity information, an amount of water to add to the breathing gasesto reach a desired humidity. The humidifier further includes theatomizer commanded by the controller to deliver the amount of water inbursts of atomized water directly into a flow path of the breathinggases and a heating element commanded by the controller to heat athermally-conductive material in the flow path downstream of theatomizer, wherein the atomized water is vaporized upon contact of thewater with the thermally-conductive material to form humidifiedbreathing gases for delivery to a patient being ventilated by theventilator.

These and various other features as well as advantages whichcharacterize the systems and methods described herein will be apparentfrom a reading of the following detailed description and a review of theassociated drawings. Additional features are set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the technology. Thebenefits and features of the technology will be realized and attained bythe structure particularly pointed out in the written description andclaims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the present disclosure asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawing figures, which form a part of this application,are illustrative of aspects of systems and methods described below andare not meant to limit the scope of the disclosure in any manner, whichscope shall be based on the claims appended hereto.

FIG. 1 is schematic diagram illustrating a first aspect of a ventilatorventilating a patient with a humidifier including an atomizer and aheating tube, in accordance with aspects of the disclosure.

FIG. 2 is schematic diagram illustrating a second aspect of a ventilatorventilating a patient with a humidifier including an atomizer, a probe,and a heating circuit, in accordance with aspects of the disclosure.

FIG. 3 is a partial, cross-sectional schematic diagram illustrating afirst aspect of a humidifier including a hollow cone atomizer in a flowpath of a ventilator during ventilation of a patient, in accordance withaspects of the disclosure.

FIG. 4 is a partial, cross-sectional schematic diagram illustrating asecond aspect of a humidifier including a hollow cone atomizer in a flowpath of a ventilator during ventilation of a patient, in accordance withaspects of the disclosure.

FIG. 5 is a partial, cross-sectional schematic diagram illustrating aspray body and a distributor of a type of hollow cone atomizer referredto as a pressure swirl atomizer, in accordance with aspects of thedisclosure.

FIG. 6 is an isometric view of a schematic diagram illustrating a spraybody of a type of hollow cone atomizer referred to as a pressure swirlatomizer, in accordance with aspects of the disclosure.

FIG. 7 is an isometric view of a schematic diagram illustrating adistributor of a type of hollow cone atomizer referred to as a pressureswirl atomizer, in accordance with aspects of the disclosure.

FIG. 8 is a partial, cross-sectional schematic diagram illustrating astand-alone humidifier including a hollow cone atomizer and a gas flowsensor, in accordance with aspects of the disclosure.

FIG. 9 is an isometric view of a schematic diagram illustrating astand-alone humidifier within a housing, in accordance with aspects ofthe disclosure.

FIGS. 10A-10D illustrate alternative spray patterns of hollow cone orfull cone atomizers, in accordance with aspects of the disclosure.

FIG. 11 is a flow diagram illustrating a method for humidifyingventilator delivered breathing gas, in accordance with aspects of thedisclosure.

DETAILED DESCRIPTION

Although the techniques introduced above and discussed in detail belowmay be implemented for a variety of medical devices, the presentdisclosure will discuss the implementation of these techniques in thecontext of a medical ventilator for use in providing ventilation supportto a human patient. A person of skill in the art will understand thatthe technology described in the context of a medical ventilator forhuman patients could be adapted for use with other systems such asventilators for non-human patients and general gas transport systems.

Medical ventilators are used to provide breathing gases to a patient whomay otherwise be unable to breathe sufficiently. In modern medicalfacilities, pressurized air and oxygen sources are often available fromwall outlets. Accordingly, ventilators may provide pressure regulatingvalves (or regulators) connected to centralized sources of pressurizedair and pressurized oxygen. The regulating valves function to regulateflow so that respiratory gases having a desired concentration of oxygenare supplied to the patient at desired pressures and rates. Ventilatorscapable of operating independently of external sources of pressurizedair are also available.

While operating a ventilator, it is desirable to control the percentageof oxygen in the gases supplied by the ventilator to the patient.Further, some ventilators are used with humidifiers to humidify thebreathing gases delivered to the patient to improve patient adherenceand comfort. However, currently utilized humidifiers often over humidifythe delivered breathing gases leading to an accumulation of water in thepatient circuit, referred to herein as “rainout.” The accumulated waterin the patient circuit can interfere with circuit sensors and/or filtersand can increase the chances of patient infection, such as pneumonia.Accordingly, the accumulated water must be removed or cleared from thepatient circuit. As such, over humidification leading to rainout isproblematic with current ventilator humidifiers. Under humidification isalso problematic, particularly in low-gas flow ventilator operatingconditions, because under humidification for prolonged periods canresult in airway damage due to dryness and other patient harm.

Accordingly, the current disclosure describes systems and methods forhumidifying ventilator delivered breathing gases that reduces and/orprevents rainout. The systems and methods as described herein utilize ahollow cone atomizer and a heating system. The heating system maycomprise a heating element associated with a heating tube or a heatingcircuit. Further, in some aspects, the system and methods as describedherein utilize received flow, temperature, and/or humidity informationto determine the amount of water to add to the breathing gases to obtaina desired percentage of relative humidity, as well as regulatingtemperature, in the breathing gases delivered to the patient. Inaspects, the humidifier may incorporate an atomizer (e.g., a hollow coneor full cone atomizer) to disperse the determined amount of water intosmall droplets that are more easily vaporized and diffused into thebreathing gases. The humidifier may be integrated into or used as astandalone device with invasive or non-invasive ventilation, a home CPAPsystem, and even “high flow” systems for use with nasal cannulas, masks,and/or helmets.

Flow, temperature, and/or humidity information may be measured by one ormore sensors located internally (e.g., at or near the inspiratory and/orexhalation modules of the ventilator), externally (e.g., integrated intothe humidifier, integrated into the patient circuit or wye fitting, orintegrated into a probe in communication with the humidifier), orcombinations thereof.

Accordingly, the systems and methods disclosed herein reduce or preventrainout in the patient circuit, reduce and/or prevent over or underhumidification, can utilize less water resulting in less filtersaturation, and can utilize a heating element having minimal warm-uptime, either in proximity to the humidifier or integrated into theventilatory tubing system. In some aspects, the use of a heating tube ora heating inspiratory limb can further minimize the need to heat theexhalation limb; in other aspects, both the inspiratory limb and theexhalation limb may be heated.

In further aspects, the humidification system can serve as anebulization system for delivering nebulized medicine. In a firstexample, a water-soluble medicine may be added to the water and thecombination of water and medicine may be vaporized and delivered to thebreathing gases by the humidifier described herein. In a second example,a second atomizer designed for the fluid characteristics of differentmedicines may be integrated into the humidifier (or provided as aremovable plug-in device to the humidifier) for delivering nebulizedmedicines into breathing gases.

FIG. 1 is a diagram illustrating a first aspect of an exemplaryventilator 100 connected to a human patient 150. Ventilator 100 includesa pneumatic system 102 (also referred to as a pressure generating system102) for circulating breathing gases to and from patient 150 via theventilation tubing system 130, which couples the patient 150 to thepneumatic system 102 via a patient interface 180, which may be aninvasive patient interface (e.g., endotracheal tube, as shown) or anon-invasive patient interface (e.g., nasal mask or nasal prongs, notshown).

Ventilation tubing system 130 (or patient circuit 130) may be a two-limb(shown) or a one-limb circuit for carrying gases to and from the patient150. In a two-limb aspect, a fitting, typically referred to as a“wye-fitting” 170, may be provided to couple the patient interface 180to an inspiratory limb 132 and an expiratory limb 134 of the ventilationtubing system 130.

Pneumatic system 102 may be configured in a variety of ways. In thepresent example, pneumatic system 102 includes an exhalation module 108coupled with the exhalation limb 134 and an inspiratory module 104coupled with the inspiratory limb 132. Compressor 106 or other source(s)of pressurized gases (e.g., air, oxygen, and/or helium) is coupled withinspiratory module 104 to provide a gas source for ventilatory supportvia inspiratory port 125 to inspiratory limb 132. The inspiratory module104 is configured to deliver breathing gases to the patient 150according to prescribed ventilatory settings. In some aspects,inspiratory module 104 is configured to provide ventilation according tovarious breath types, e.g., via volume-control, pressure-control,proportional assist control, or via any other suitable breath types. Theexhalation module 108 is configured to release gases from the patient'slungs according to prescribed ventilatory settings. Specifically,exhalation module 108 is associated with and/or controls an exhalationvalve for releasing gases from the patient 150.

The ventilator 100 may also include one or more sensors 107communicatively coupled to ventilator 100. The sensors 107 may belocated in the pneumatic system 102, ventilation tubing system 130,and/or on the patient 150. FIG. 1 illustrates an example of a sensor 107in pneumatic system 102. Sensors 107 may communicate with variouscomponents of ventilator 100, e.g., pneumatic system 102, other sensors107, processor 116, humidifier 118, heating tube 119, and/or any othersuitable components and/or modules. A module as used herein refers tomemory, one or more processors, storage, and/or other components of thetype commonly found in command and control computing devices.

In one aspect, sensors 107 generate output and send this output topneumatic system 102, other sensors 107, processor 116, controller 110,humidifier 118, heating element of heating tube 119, and/or any othersuitable components and/or modules. Sensors 107 may employ any suitablesensory or derivative technique for monitoring one or more patientparameters or ventilator parameters associated with the ventilation of apatient 150. Sensors 107 may detect changes in patient parametersindicative of patient triggering, for example. In other examples, thesensor 107 may include a humidity sensor, a temperature sensor, acombined temperature/humidity sensor, and/or inspiratory flow sensor. Insome aspects, the humidity sensor determines the humidity andtemperature of the breathing gas. In other aspects, the inspiratory flowsensor determine the inspiratory flow rate of the breathing gas.

Sensors 107 may be placed in any suitable location, e.g., within theventilatory circuitry or other devices communicatively coupled to theventilator 100. Further, sensors 107 may be placed in any suitableinternal location, such as, within the ventilatory circuitry or withincomponents or modules of ventilator 100. For example, sensors 107 may becoupled to the inspiratory and/or exhalation modules for detectingchanges in, for example, circuit pressure and/or flow. In otherexamples, sensors 107 may be affixed to the ventilatory tubing or may beembedded in the tubing itself. According to some aspects, sensors 107may be provided at or near the lungs (or diaphragm) for detecting apressure in the lungs. Additionally or alternatively, sensors 107 may beaffixed or embedded in or near wye-fitting 170 and/or patient interface180.

Indeed, any sensory device useful for monitoring changes in measurableparameters during ventilatory treatment may be employed in accordancewith aspects described herein.

As should be appreciated, with reference to the Equation of Motion,ventilatory parameters are highly interrelated and, according toaspects, may be either directly or indirectly monitored. That is,parameters may be directly monitored by one or more sensors 107, asdescribed above, or may be indirectly monitored or estimated/calculatedusing a model, such as a model derived from the Equation of Motion:

Target Airway Pressure(t)=E _(p) ∫Q _(p) dt+Q _(p) R _(p)−PatientEffort(t)

The pneumatic system 102 may include a variety of other components,including mixing modules, valves, tubing, accumulators, filters,humidifier 118, heating tube 119, water reservoir 121, etc. In otheraspects, these other components are located outside of the pneumaticsystem 102, such as the mixing modules, valves, tubing, accumulators,filters, humidifier 118, heating tube 119, water reservoir 121, etc.

Controller 110 is operatively coupled with pneumatic system 102, signalmeasurement and acquisition systems, and an operator interface 120 thatmay enable an operator to interact with the ventilator 100 (e.g., changeventilator settings, select operational modes, view monitoredparameters, etc.). In some aspects, the controller in electroniccommunication with and/or operatively coupled to a humidifier 118 and/ora heating tube 119. For example, the controller 110 of the ventilator100 may send an inspiratory flow command, inspiratory flow measurements,and/or temperature or humidity measurements of the breathing gases tothe humidifier 118 and/or a heating tube 119.

In one aspect, the operator interface 120 of the ventilator 100 includesa display 122 communicatively coupled to ventilator 100. Display 122provides various input screens, for receiving clinician input, andvarious display screens, for presenting useful information to theclinician. In one aspect, the display 122 is configured to include agraphical user interface (GUI). The GUI may be an interactive display,e.g., a touch-sensitive screen or otherwise, and may provide variouswindows and elements for receiving input and interface commandoperations. Alternatively, other suitable means of communication withthe ventilator 100 may be provided, for instance by a wheel, keyboard,mouse, or other suitable interactive device. Thus, operator interface120 may accept commands and input through display 122. Display 122 mayalso provide useful information in the form of various ventilatory dataregarding the physical condition of a patient 150. The usefulinformation may be derived by the ventilator 100, based on datacollected by a processor 116, and the useful information may bedisplayed to the clinician in the form of graphs, wave representations,pie graphs, text, or other suitable forms of graphic display. Forexample, patient data may be displayed on the GUI and/or display 122.Additionally or alternatively, patient data may be communicated to aremote monitoring system coupled via any suitable means to theventilator 100. In one aspect, the display 122 may display one or moreof a flow rate, a relative humidity of the breathing gases, atemperature of the breathing gases, a selected breath type, a humidifieron or a humidifier off status, etc.

Controller 110 may include memory 112, one or more processors 116,storage 114, and/or other components of the type commonly found incommand and control computing devices. The memory 112 includesnon-transitory, computer-readable storage media that stores and/orencodes software (such as computer executable instruction) that isexecuted by the processor 116 and which controls the operation of theventilator 100. In an aspect, the memory 112 includes one or moresolid-state storage devices such as flash memory chips. In analternative aspect, the memory 112 may be mass storage connected to theprocessor 116 through a mass storage controller (not shown) and acommunications bus (not shown). Although the description ofcomputer-readable media contained herein refers to a solid-statestorage, it should be appreciated by those skilled in the art thatcomputer-readable storage media can be any available media that can beaccessed by the processor 116. That is, computer-readable storage mediaincludes non-transitory, volatile and non-volatile, removable andnon-removable media implemented in any method or technology for storageof information such as computer-readable instructions, data structures,program modules or other data. For example, computer-readable storagemedia includes RAM, ROM, EPROM, EEPROM, flash memory or other solidstate memory technology, CD-ROM, DVD, or other optical storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to store thedesired information and which can be accessed by the computer.

As illustrated by FIG. 1, the ventilator 100 also includes a humidifier118 located upstream or directly upstream of heating tube 119. In someaspects, the humidifier 118 includes the heating tube 119 (not shown);while in other aspects, the heating tube 119 is separate from andindependent of the humidifier 118 (as shown). In aspects, as illustratedby FIG. 1, humidifier 118 may be a stand-alone device, including acontroller and processors for monitoring and regulating humidity of thebreathing gases, as well as including an independent gas flow sensor. Inthis case, humidifier 118 may be installed outside of the ventilator 100near inspiratory port 125 and may be independently powered via powerinterface 123. In other aspects (not shown), humidifier 118 includingheating tube 119 may be utilized in conjunction with a heating circuit(such as heating circuit 230). In some aspects, illustrated by FIGS. 3and 4, humidifier 118 may be integrated with the ventilator 100, mayinclude a controller and processors for monitoring and regulatinghumidity of the breathing gases, but may not include an independent gasflow sensor. In still other aspects, humidifier 118 may be integratedwith and controlled by ventilator 100 via controller 110, may notcomprise an independent gas flow sensor, and may also be powered byventilator 100 (not shown). Whether the humidifier 118 is integratedwith the ventilator or is a stand-alone device, the humidifier 118 mayaccess a water supply via water reservoir 121, which may be independentof (as shown) or integrated with ventilator 100. Additionally, the watersupply accessed by humidifier 118 may be filtered by a water filter (notshown). In some cases, a medicine may be dissolved in the water supply,e.g., where the water supply is an intravenous (IV) bag.

Heating tube 119 may form a short conduit (e.g., two to five incheslong) downstream of humidifier 118 (shown) and upstream of inspiratorylimb 132. Alternatively, heating tube 119 may be integrated intohumidifier 118 (not shown) and may form a short conduit upstream ofinspiratory limb 132. As noted above and illustrated in FIG. 2, heatingtube 119 may form a short conduit upstream of heating inspiratory limb232 (not shown). Heating tube 119 may comprise a thermally-conductivematerial, such as aluminum, silver, copper, or other suitable metal oralloy (which, in some cases may be thinly plated with nickel to preventcorrosion), and a heating element. In some aspects, the heating elementmay be a heater blanket surrounding the thermally conductive material ofheating tube 119. The heating element may generate thermal energy viaany suitable means, e.g., electrical, chemical, or otherwise, and maydeliver the thermal energy to the thermally-conductive material via anysuitable means (e.g., via an external sleeve or blanket, internal orexternal wiring, etc.). In aspects, the heating element may heatquickly, e.g., in less than one minute, and may be controlled byhumidifier 118 and/or ventilator 100 to achieve a desired temperature.As illustrated, heating tube 119 is in fluid communication with theinspiratory limb 132 of the ventilation tubing system 130. In this way,heating tube 119 contacts air or liquid in the flow path for maintaininga desired humidity of the breathing gases and preventing rainout in theventilation tubing system 130. In some aspects, a second heating tube(not shown) may be placed on the exhalation side of the wye fitting 170in order to maintain a desired humidity of exhaled gases and to preventrainout in the exhalation limb 134 of the ventilation tubing system 130.

In some aspects, the humidifier 118 also includes a controller (similarto controller 110) with a memory (similar to memory 112), one or moreprocessors (similar to processors 116), storage (similar to storage114), a display (similar to display 122) and/or other components of thetype commonly found in command and control computing devices similar tothe ones described above for the ventilator 100. In some cases, whenhumidifier 118 includes one or more of the above-described components ofcommand and control computing devices, the humidifier 118 may beintegrated with ventilator 100; in other cases, the humidifier 118 maybe a stand-alone unit that is communicatively coupled to ventilator 100.As used herein, communicatively or operatively coupled refers to anywired or wireless communication infrastructure configured for receivingand/or transmitting commands, data, measurements, or other information.In some cases, whether the humidifier 118 is integrated with theventilator 100 or is a stand-alone unit, the humidifier may beindependently powered via power interface 123.

When humidifier 118 includes one or more of the above-describedcomponents of command and control computing devices (not shown), thehumidifier memory includes non-transitory, computer-readable storagemedia that stores and/or encodes software (such as computer executableinstruction) that is executed by the humidifier processor and whichcontrols the operation of the humidifier 118. In an aspect, thehumidifier memory includes one or more solid-state storage devices suchas flash memory chips. In an alternative aspect, the humidifier memorymay be mass storage connected to the humidifier processor through a massstorage controller (not shown) and a communications bus (not shown).Although the description of computer-readable media contained hereinrefers to a solid-state storage, it should be appreciated by thoseskilled in the art that computer-readable storage media can be anyavailable media that can be accessed by the humidifier processor. Thatis, computer-readable storage media includes non-transitory, volatileand non-volatile, removable and non-removable media implemented in anymethod or technology for storage of information such ascomputer-readable instructions, data structures, program modules orother data. For example, computer-readable storage media includes RAM,ROM, EPROM, EEPROM, flash memory or other solid state memory technology,CD-ROM, DVD, or other optical storage, magnetic cassettes, magnetictape, magnetic disk storage or other magnetic storage devices, or anyother medium which can be used to store the desired information andwhich can be accessed by the computer.

FIG. 2 is a diagram illustrating a second aspect of an exemplaryventilator 200 connected to a human patient 150. Similar to ventilator100, ventilator 200 includes a pneumatic system 102 for circulatingbreathing gases to and from patient 150 via a ventilation tubing system,which couples the patient 150 to the pneumatic system 102 via a patientinterface 180 (e.g., endotracheal tube, as shown). Other than thecomponents described below, the components of ventilator 200 aresimilarly described to the components of ventilator 100. Similar toventilator 100, ventilator 200 is communicatively coupled to ahumidifier 218. However, in the second aspect illustrated by FIG. 2,humidifier 218 does not comprise heating tube 119 but is communicativelycoupled to a heating circuit 230 and/or a probe 236.

Heating circuit 230 may comprise a heating inspiratory limb 232 and/or aheating exhalation limb 234. Unlike heating tube 119, which is incontact with a minimal portion of a patient circuit, heating circuit 230may comprise a heating element (depicted by dashed lines) that is incontact with a substantial portion of the patient circuit, including aheating inspiratory limb 232 and/or a heating exhalation limb 234. Theheating element may be independent and may surround (e.g., as a heaterblanket) a traditional, disposable patient circuit to form heatingcircuit 230. In this case, the heating element may be non-disposable andcapable of sterilization between patients; or the heating element mayitself be disposable. Alternatively, the heating element may beintegrated (e.g., wired) into a custom, disposable patient circuit toform heating circuit 230. The heating element may generate thermalenergy via any suitable means, e.g., electrical, chemical, or otherwise,and may deliver the thermal energy to heat the patient circuit via anysuitable means (e.g., via an external sleeve or blanket, internal orexternal wiring, etc.). In aspects, the heating element may heatquickly, e.g., in one minute or less, and may be controlled byhumidifier 218, probe 236, and/or ventilator 100 to achieve a desiredtemperature.

As illustrated, heating circuit 230 comprises heating inspiratory limb232 (depicted by dashed lines) and heating exhalation limb 234 (depictedby dashed lines) and is in substantial fluid communication withbreathing gases and exhalation gases to regulate humidity and preventrainout in heating circuit 230. The purpose of heating the inspiratorylimb is to heat the humidified breathing gases in order to control atemperature of the breathing gases at the wye fitting (e.g., between 32and 42 degrees C.), to provide further evaporative heating power (or toprovide all of the evaporative heating power required to vaporize theinjected water when the humidifier does not include a heating tube), andto prevent condensation of water on the inside walls of the inspiratorylimb. The purpose of heating the exhalation limb is to heat exhalationgases to prevent condensation from forming on the inside walls, so thetemperature in the heating exhalation limb 234 should be maintained at alevel just above the dew point of the exhaled gases (for examplemaintained at 44 degrees C.). Alternatively, heating circuit 230 maycomprise heating inspiratory limb 232 without heating exhalation limb234. In this case, heating inspiratory limb 232 may regulate temperatureof the humidified breathing gases and may prevent rainout in the heatinginspiratory limb 232 as well as minimizing rainout the non-heatedexhalation limb 134 (not shown).

Probe 236 may be communicatively coupled to or integrated into wyefitting 170 (depicted by a two-way arrow). In one example, probe 236comprises a temperature sensor and/or humidity sensor (not shown) formonitoring the temperature and/or humidity of the constituents (e.g.,breathing gas and water) flowing through heating circuit 230. In anotherexample, probe 236 is communicatively coupled to a temperature sensorand/or humidity sensor (not shown) associated with the wye fitting 170for monitoring the temperature and/or humidity of the constituents(e.g., breathing gas and water) flowing through heating circuit 230. Thetemperature and/or humidity sensor is similar to temperature and/orhumidity sensor 107, as described above. In further aspects, probe 236is communicatively coupled to humidifier 118 (depicted by a two-wayarrow) and may provide feedback to humidifier 218 regarding thetemperature and/or humidity of breathing gases flowing to patient 150and/or exhalation gases flowing back to the ventilator 200. Based on thefeedback from probe 236, humidifier 218 may adjust an amount of waterdelivered to the flow path and/or may adjust an amount of heat deliveredby the heating element to heating circuit 230.

FIG. 3 is a partial cross-sectional schematic diagram illustrating afirst aspect of a humidifier 300 (similar to humidifier 118 orhumidifier 218, detailed above) including a hollow cone atomizer 302 ina flow path 304 of a ventilator (similar to ventilator 100 or ventilator200, detailed above) during ventilation of a patient 150, in accordancewith aspects of the disclosure. As illustrated, humidifier 300 does notcomprise a gas flow sensor and is integrated with the ventilator (e.g.,ventilator 100 or ventilator 200). As with humidifier 118, humidifier300 comprises a heating tube 319 (similar to heating tube 119). Whilehumidifier 300 is not shown in fluid communication with a heatinginspiratory limb (e.g., such as heating inspiratory limb 232), thisconfiguration is contemplated and humidifier 300 may easily beimplemented in such a system. In aspects, the hollow cone atomizer 302may be a pressure swirl atomizer. As illustrated, the hollow coneatomizer 302 is positioned to spray water (or water and medicine)directly into the flow path 304 of the breathing gases, which gases mayexhibit variable initial humidity levels. For instance, if the breathinggas source is dry, such as from bottled gases, hospital wall gases, orgases from a compressor with dryer, then a greater amount of water wouldneed to be injected into the breathing gas stream than would be thecase, for example, if the breathing gas source is from a blower-basedsystem that provides gases at an ambient humidity level. As humidifier300 is integrated with the ventilator, the flow path 304 is within thepressure generating system 102. Alternatively, where the humidifier is astand-alone device, the flow path may be downstream from the pressuregenerating system 102 but upstream from the ventilator tubing system130, as illustrated in FIG. 1.

In some aspects, a second atomizer (not shown) may be provided in theflow path 304 passing through the humidifier 300. In this case, thesecond atomizer may be designed based on the fluid characteristics of amedicine or medicines to be delivered. For instance, when medicines arenot water-soluble, these medicines may be significantly more viscousthan water, and therefore the dimensions of the atomizer may need to beadjusted to appropriately atomize the medicine. Depending on the fluidcharacteristics, this second atomizer may be a more conventional(non-pressure swirl) atomizer type. The second atomizer may use the sametype of reservoir, pumping and valve system, as described below.Alternatively, depending on the fluid characteristics of the medicine,the second atomizer may require adjustments to the reservoir, pumping,and/or valve system as appropriate for the fluids and the pressuresused. In aspects, a medicine dissolved in a biologically-compatiblesolvent is delivered to the second atomizer via a suitable valve and/orpumping system. Similar to the first atomizer, the second atomizerdisperses the medicine-solvent solution in small droplets into the flowpath. Depending on the location of the second atomizer with respect tothe heated tube 319, and the fluid characteristics of themedicine-solvent solution, the small droplets may or may not bevaporized by the humidifier 300. However, it is contemplated that smalldroplets of the medicine-solvent may deliver a prescribed amount of themedicine to the breathing gases without requiring vaporization. Whilethe second atomizer could be located before or after the first atomizer(e.g., atomizer 302), the preferred location is downstream of the firstatomizer and the heated tube 319. In some cases, the second atomizer maybe a removable plug-in device, e.g., connected via an access port in thehumidifier housing that may be covered when not in use.

In some aspects, the humidifier 300 also includes a water reservoir 321,a high-pressure water pump 318 and a valve 316, which are in fluidcommunication with the hollow cone atomizer 302. For example, the waterpump 316 pumps water from the water reservoir 321 towards the hollowcone atomizer 302 through valve 316. The water reservoir 321, such as anintravenous (IV) bag of distilled water or other suitable water supply,supplies water at ambient pressure to the water pump 318. In some cases,a medication may be dissolved in the water reservoir 321, e.g.,dissolved in the intravenous (IV) bag. An outlet of the water pump 318is directed to the valve 316. In some aspects, the valve 316 is afast-response solenoid valve that delivers high-pressure water to thehollow cone atomizer 302.

As illustrated, humidifier 300 further includes a controller 310including memory 312 and at least one processor 314. Controller 310 maybe operative to receive an inspiratory flow command from the ventilator(e.g., ventilator 100) and may command valve 316 to deliver an amount ofwater sufficient to maintain a user-selected relative humidity of thebreathing gases. In further aspects, the controller 310 may commandvalve 316 to deliver an amount of water including a dissolved orsuspended medicine. In this case, the amount of water may be calculatedto be sufficient to maintain the user-selected relative humidity of thebreathing gases as well as to deliver a prescribed amount of themedicine based on a concentration of the medicine in the water. Inaspects, a concentration of the medicine may be adjusted based on theamount of water calculated to maintain the desired humidity. In otheraspects, as detailed above, humidifier 300 may not include a controllerand valve 316 may be controlled by the ventilator (e.g., ventilator100). In the depicted aspect, controller 310 may command valve 316 usingPulse Width Modulation (PWM) or some other suitable driving method toprovide “bursts” of water to the hollow cone atomizer 302. In theseaspects, the duration and timing of bursts (as controlled by the openingand closing of the valve 316) provides a prescribed amount ofhigh-pressure water to the hollow cone atomizer 302. These controlledbursts or pulses allow the hollow cone atomizer 302 to deliver aspecific amount of atomized water (e.g., in a cone pattern of extremelysmall water droplets) to the gas stream, thereby preventing or reducingover or under humidification as well as delivering a prescribed amountof a dissolved medicine, if desired.

Additionally, the hollow cone atomizer 302 is configured to spray water(or water and medicine) in a hollow-cone pattern of extremely smallwater droplets at a low flow rate. The low flow rate further enables thehollow cone atomizer 302 to prevent or reduce over humidification. Insome aspects, to achieve a desired humidity, the water flow rate isdependent on the gas flow rate. For instance, an average water flow rateas low as 0.04 ml/min may be delivered at a gas flow rate of 1liters/min; whereas an average water flow rate as high as 9 ml/min maybe delivered at a gas flow of 200 liters/min. The atomizer is designedto provide a minimum water flow rate of at least 9 ml/min so it canaccommodate the maximum gas flow rate of 200 liters/min. Thus, toaccommodate lower gas flow rates, the solenoid valve may be pulsed withshorter durations and/or longer intervals between pulses to deliver lesswater flow. In this case, the atomizer may deliver pulses of water at 30ml/min timed and spaced to provide an average water flow rate of 1ml/min. Even at a higher water flow rates, unlike other atomizers, ahollow cone atomizer may be utilized with shorter durations and longerintervals that are still short enough to provide consistenthumidification.

In general, the hollow cone atomizer may be configured to deliver awater flow rate from 0.1 to 40.0 ml/min to breathing gases flowing bythe hollow cone atomizer 302 in the flow path 304 exhibiting a gas flowrate from 1 to 200 liters/min. These water flow rates are exemplary onlyand not meant to be limiting. Other suitable water flow rates for usewith the hollow cone atomizer are known by a person of skill in the art.In some aspects, the humidifier 300 also includes a water filter 313.The water filter 313 prevents small debris from entering the water pump318, the valve 316, and/or the hollow cone atomizer 302 by filtering outany debris from the water supply. As illustrated, the water filter 313is located upstream of the water pump 318, the valve 316, and the hollowcone atomizer 302. In other aspects, the water filter 313 may be locateddownstream of the water pump 318 and upstream of the valve 316 and thehollow cone atomizer 302.

As illustrated, the humidifier 300 also includes a temperature sensorand/or humidity sensor 307 located in flow path 304 upstream of thehollow cone atomizer 302. In other aspects, a temperature senor and/or ahumidity sensor 307 may be located within the ventilator (e.g.,associated with the inspiratory module 104) upstream of the hollow coneatomizer 302 but separate and distinct from the humidifier 300. In theseaspects, the temperature sensor and/or a humidity sensor 307 is not partof the humidifier 300 but is part of the ventilator (e.g., ventilator100). The temperature sensor and/or humidity sensor 307 may becommunicatively coupled to humidifier 300 and may provide temperatureand/or humidity measurements to controller 310, which may then commandthe heating tube 319 (and/or a heating circuit, not shown) to maintain adesired temperature and/or humidity of the breathing gases flowingthrough flow path 304. Alternatively, the temperature sensor and/orhumidity sensor 307 may provide temperature and/or humidity measurementsto controller 110 of ventilator 100 and ventilator 100 may then commandheating tube 319 (and/or a heating circuit, not shown) to maintain adesired temperature and/or humidity of the breathing gases flowingthrough flow path 304.

As illustrated, the humidifier 300 also includes a heating tube 319. Theheating tube 319 includes a thermally-conductive material 306, such asaluminum, silver, copper, or other suitable metal or alloy (which, insome cases may be thinly plated with nickel to prevent corrosion), whichis surrounded by a heating element 308. The heating element 308 maygenerate thermal energy via any suitable means, e.g., electrical,chemical, or otherwise, and may deliver the thermal energy to thethermally-conductive material 306 via any suitable means (e.g., via anexternal sleeve or blanket, internal or external wiring, etc.). Asillustrated in FIG. 3, the heating tube 319 is in fluid communicationwith an inspiratory limb (e.g., inspiratory limb 132) of the ventilationtubing system (e.g., ventilation tubing system 130) along flow path 304.As further illustrated in FIG. 3, the thermally-conductive material 306is exposed in the flow path 304 and contacts the breathing gases orwater in the flow path 304. The heating element 308 surrounds thethermally-conductive material 306 and is not in contact with breathinggases or water in the flow path 304. In aspects, the heating element 308may heat quickly, e.g., in one minute or less, and may be controlled byhumidifier 300 and/or ventilator 100 to rapidly achieve a desiredtemperature of the breathing gases within heating tube 319. As such,ventilator 100 and/or humidifier 300 require very little start up timefor humidifying the breathing gas.

The heating tube 319 is positioned directly downstream of the hollowcone atomizer 302, such that water sprayed from the hollow cone atomizercontacts the thermally-conductive material 306 of the heating tube 319.When the thin, hollow cone 323 of small droplets of water from thehollow cone atomizer 302 contacts the heated metal surface of thethermally-conductive material 306, the small droplets of water areimmediately vaporized, turning into gaseous water vapor. This gaseouswater vapor enters the stream of breathing gases 325 in flow path 304,forming a gaseous solution of humidified breathing gases 330. In someaspects, the temperature of the heating tube 319 is maintained usingclosed-loop control by controller 310 (or controller 110 of ventilator100) to a level whereby the droplets emitted from the hollow coneatomizer 302 are vaporized, and a temperature of the humidifiedbreathing gases 330 is regulated to maintain the water vapor in thebreathing gases delivered to the patient at a user-selected humidity.For instance, in embodiments without a heated circuit, for a patient setpoint of 37 degrees C., the humidified breathing gases leaving thehumidifier may be about 45 degrees C. to account for cooling in theinspiratory limb of the patient circuit. In other aspects, thetemperature of the heating tube 319 is significantly hotter than neededfor vaporization in order to raise the temperature of the humidifiedbreathing gases 330 to a desired temperature sufficient to maintain thewater vapor in the breathing gases at the user-selected humidity whencooling occurs in the ventilation tubing system. In aspects, the heatingtube 319 may have a length from 2 inches to 7 inches. In some aspectsthe heating tube 319 has a length of 2 inches, 3 inches, or 4 inches.

FIG. 4 is a partial cross-sectional schematic diagram illustrating asecond aspect of a humidifier 400 (similar to humidifier 218, detailedabove) including a hollow cone atomizer 402 in a flow path 404 of aventilator (similar to ventilator 200, detailed above) duringventilation of a patient 150, in accordance with aspects of thedisclosure. As illustrated, humidifier 400 does not comprise a gas flowsensor and is integrated with the ventilator (e.g., ventilator 200).Unlike humidifier 300, humidifier 400 does not comprise a heating tubebut delivers humidified breathing gases 430 to a heating inspiratorylimb 406 (similar to heating inspiratory limb 232). However, in aspects,as detailed above, humidifier 400 may also be configured with a heatingtube (such as heating tube 319) and be implemented with a heatinginspiratory limb 406 and a heated exhalation limb (such as heatedexhalation limb 234). In aspects, the hollow cone atomizer 402 may be apressure swirl atomizer. As illustrated, the hollow cone atomizer 402 ispositioned to spray water (or water and medicine) directly into the flowpath 404 of the breathing gases. As humidifier 400 is integrated withthe ventilator, the flow path 404 is within the pressure generatingsystem 102 of ventilator 200. However, where the humidifier is astand-alone device, the flow path is downstream from the pressuregenerating system 102 but upstream from the heating circuit 230, asillustrated in FIG. 2.

In some aspects, the humidifier 400 also includes a water reservoir 421,a high-pressure water pump 418 and a valve 416, which are in fluidcommunication with the hollow cone atomizer 402. For example, the waterpump 416 pumps water from the water reservoir 421 towards the hollowcone atomizer 402 through valve 416. In some aspects, the valve 416 is afast-response solenoid valve that delivers high-pressure water to thehollow cone atomizer 402. In some cases, the water may comprise adissolved medicine at a known concentration.

As illustrated, humidifier 400 further includes a controller 410including memory 412 and at least one processor 414. Controller 410 maybe operative to receive an inspiratory flow command from the ventilator(e.g., ventilator 200) and may command valve 416 to deliver an amount ofwater sufficient to maintain a user-selected relative humidity of thebreathing gases. In other aspects, as detailed above, humidifier 400 maynot include a controller and valve 416 may be controlled by theventilator (e.g., ventilator 200). In the depicted aspect, controller410 may command valve 416 using Pulse Width Modulation to provide“bursts” of water to the hollow cone atomizer 402. In these aspects, theduration and timing of bursts (as controlled by the opening and closingof the valve 416) provides a prescribed amount of high-pressure water tothe hollow cone atomizer 402. These controlled bursts or pulses allowthe hollow cone atomizer 402 to deliver a specific amount of atomizedwater (e.g., in a cone pattern of extremely small water droplets) to thegas stream, thereby preventing or reducing over or under humidification.

As with humidifier 300, humidifier 400 may include a second atomizer(not shown) in flow path 404. In this case, the second atomizer may bedesigned based on the fluid characteristics of a medicine or medicinesto be delivered. For instance, when medicines are not water-soluble,these medicines may be significantly more viscous than water, andtherefore the dimensions of the atomizer may need to be adjusted toappropriately atomize the medicine. Depending on the fluidcharacteristics, this second atomizer may be a more conventional(non-pressure swirl) atomizer type. The second atomizer may use the sametype of reservoir, pumping and valve system, as described below.Alternatively, depending on the fluid characteristics of the medicine,the second atomizer may require adjustments to the reservoir, pumping,and/or valve system as appropriate for the fluids and the pressuresused. In aspects, a medicine dissolved in a biologically-compatiblesolvent is delivered to the second atomizer via a suitable valve and/orpumping system. Similar to the first atomizer, the second atomizerdisperses the medicine-solvent solution in small droplets into the flowpath. Depending on the location of the second atomizer and the fluidcharacteristics of the medicine-solvent solution, the small droplets mayor may not be vaporized by the humidifier 400. However, it iscontemplated that small droplets of the medicine-solvent may deliver aprescribed amount of the medicine to the breathing gases withoutrequiring vaporization. While the second atomizer could be locatedbefore or after the first atomizer (e.g., atomizer 402), the preferredlocation is downstream of the first atomizer. In some cases, the secondatomizer may be a removable plug-in device, e.g., connected via anaccess port in the humidifier housing that may be covered when not inuse.

As with hollow cone atomizer 302, the hollow cone atomizer 402 isconfigured to spray water (or water and medicine) in a hollow-conepattern of extremely small water droplets at a low flow rate. The lowflow rate further enables the hollow cone atomizer 402 to prevent orreduce over humidification. As detailed above, the hollow cone atomizermay be configured to deliver a water flow rate from 0.1 to 40.0 ml/minto breathing gases flowing by the hollow cone atomizer 402 in the flowpath 404 exhibiting a gas flow rate from 1 to 200 liters/min. Thesewater flow rates are exemplary only and not meant to be limiting. Othersuitable water flow rates for use with the hollow cone atomizer 402 areknown by a person of skill in the art. In some aspects, the humidifier400 also includes a water filter 413. The water filter 413 preventssmall debris from entering the water pump 418, the valve 416, and/or thehollow cone atomizer 402 by filtering out any debris from the watersupply. As illustrated, the water filter 413 is located upstream of thewater pump 418, the valve 416, and the hollow cone atomizer 402. Inother aspects, the water filter 413 may be located downstream of thewater pump 418 and upstream of the valve 416 and the hollow coneatomizer 402.

As illustrated, the humidifier 400 also includes a temperature sensorand/or humidity sensor 407 located in flow path 404 upstream of thehollow cone atomizer 402. In other aspects, a temperature senor and/or ahumidity sensor 407 may be located within the ventilator (e.g.,associated with the inspiratory module 104) upstream of the hollow coneatomizer 402 but separate and distinct from the humidifier 400. In theseaspects, the temperature sensor and/or a humidity sensor 407 is not partof the humidifier 400 but is part of the ventilator (e.g., ventilator200). The temperature sensor and/or humidity sensor 307 may becommunicatively coupled to humidifier 400 and may provide temperatureand/or humidity measurements to controller 410, which may then commandthe heating element 408 (or the heating tube, not shown) to maintain adesired temperature and/or humidity of the breathing gases flowingthrough flow path 404. Alternatively, the temperature sensor and/orhumidity sensor 407 may provide temperature and/or humidity measurementsto controller 110 of ventilator 200 and ventilator 200 may then commandheating element 408 (or the heating tube, not shown) to maintain adesired temperature and/or humidity of the breathing gases flowingthrough flow path 404.

Unlike humidifier 300, the humidifier 400 does not include a heatingtube. However, humidifier 400 is in fluid communication with a heatinginspiratory limb 406 (similar to heating inspiratory limb 232). Unlikeheating tube 319, which is in contact with a minimal portion of apatient circuit, a heating circuit (similar to heating circuit 230) maycomprise a heating element 408 (depicted by dashed lines) that is incontact with a substantial portion of the patient circuit, includingheating inspiratory limb 406 and/or a heating exhalation limb (notshown). The heating element 408 may be independent and may surround(e.g., as a heater blanket or heater sleeve) a traditional, disposablepatient circuit to form the heating inspiratory limb 406. In this case,the heating element 408 may be non-disposable and capable ofsterilization between patients; or the heating element may itself bedisposable. Alternatively, the heating element 408 may be integrated(e.g., wired) on the exterior or the interior of a custom, disposablepatient circuit to form the heating inspiratory limb 406. The heatingelement 408 may generate thermal energy via any suitable means, e.g.,electrical, chemical, or otherwise, and may deliver the thermal energyto heat the patient circuit via any suitable means (e.g., via anexternal sleeve or blanket, internal or external wiring, etc.). Inaspects, the heating element 408 may heat quickly, e.g., in a minute orless, and may be controlled by humidifier 400, a probe (such as probe236), and/or ventilator 200 to achieve a desired temperature. Asillustrated, heating inspiratory limb 406 is in substantial fluidcommunication with humidified breathing gases 430 to regulate humidityand prevent rainout in heating inspiratory limb 406. In some cases, aheating circuit may comprise heating inspiratory limb 406 without aheating exhalation limb. In this case, heating inspiratory limb 406 mayregulate temperature of the humidified breathing gases 430 and mayprevent rainout in the heating inspiratory limb 406 as well asminimizing rainout the non-heated exhalation limb (not shown).

As illustrated, the heating inspiratory limb 406 is positioned directlydownstream of the humidifier 400, such that atomized water from thehollow cone atomizer 402 contacts the heating inspiratory limb 406. Forexample, when the hollow cone 423 of small droplets of water from thehollow cone atomizer 402 contact the heated surface of the heatinginspiratory limb 406, the small droplets of water are vaporized, turninginto gaseous water vapor. This gaseous water vapor enters the stream ofbreathing gases 425 in flow path 404, forming a gaseous solution ofhumidified breathing gases 430. Alternatively, as discussed above,humidifier 400 may further comprise a heating tube (not shown). In thiscase, humidified breathing gases leaving the humidifier 400 enter theheating inspiratory limb 406, which is modulated to control thetemperature of the breathing gases at the patient wye fitting 170. Insome aspects, the heating inspiratory limb 406 is controlled such that atemperature gradient exists whereby the temperature at the entrance ofthe heating inspiratory limb 406 is higher than at the exit (wye fitting170) due to the heating tube (e.g., heating tube 319) upstream of theheating inspiratory limb 406. In other aspects, humidifier 400 does notinclude a heating tube (as shown) and the heating and water vaporizationare achieved using the heating inspiratory limb 406 alone. In someaspects, the temperature of the heating inspiratory limb 406 ismaintained using closed-loop control by controller 410 (or controller110 of ventilator 200) to a level whereby the droplets emitted from thehollow cone atomizer 402 are vaporized, and a temperature of thehumidified breathing gases 430 within the heating inspiratory limb 406may be regulated to maintain an amount of water vapor in the breathinggases delivered to the patient at a user-selected humidity. In somecases, as described with respect to FIG. 2, feedback from a probe (suchas probe 236) may provide temperature and/or humidity measurements ofthe humidified breathing gases 430 at the wye fitting 170 to thecontroller 410 (or the controller 110). In this way, the heating element408 may be adjusted to increase or decrease a temperature of the heatinginspiratory limb 406 in order to maintain the user-selected humidity ofthe breathing gases at the wye fitting 170.

FIG. 5 is a partial cross-sectional schematic diagram illustrating aspray body 506 and a distributor 508 of a type of hollow cone atomizerreferred to as a pressure swirl atomizer 500, in accordance with aspectsof the disclosure. A pressure swirl atomizer is a type of hollow coneatomizer that delivers high performance atomization at low liquid flowrates. FIG. 6 is an isometric view of a schematic diagram illustrating aspray body 606 of a type of hollow cone atomizer referred to as apressure swirl atomizer 600, in accordance with aspects of thedisclosure. FIG. 7 is an isometric view of a schematic diagramillustrating a distributor 708 of a type of hollow cone atomizerreferred to as a pressure swirl atomizer 700, in accordance with aspectsof the disclosure.

As illustrated in FIGS. 5 and 6, a discharge orifice 520 (or 620) on thespray body 506 (or 606) extends through a first end 521 (or 621) of thespray body 506 (or 606) and connects to an interior passageway 526within the spray body 506 (not shown in FIG. 6). The first end 521 (or621) has an exterior wall 523 (or 623) and an interior wall 525.

As illustrated in FIG. 5, the distributor 508 is received within theinterior passageway 526 of the spray body 506 and mechanically biasedagainst the interior wall 525 of the first end 521 of the spray body506. In some aspects, the distributor 508 is mechanically biased with aresilient material, such as a spring. In further aspects, a swirlchamber 522 of the distributor 508 abuts and is in fluid communicationwith the discharge orifice 520.

As illustrated by FIG. 7, a single inlet channel 728 in the distributor708 provides a passageway or opening for water to flow from an interiorpassageway (e.g., interior passageway 526 of FIG. 5) to the swirlchamber 722 (or 522). In some aspects, the water flows through theinternal passageway 526, a distributor passage 532, one or more passageapertures 530 (or 730), and/or a high pressure water port 524 to reachthe inlet channel 728.

When high pressure water (or water and medicine) (generally greater than50 psi, such as 300 psi) enters the spray body 506 (or 606) of thepressure swirl atomizer 500 (or 600), the water is ported to a singleinlet channel 728 (as illustrated in FIG. 7). Although some hollow coneatomizers may include more than one inlet channel (not shown), practicalapplications for such hollow cone atomizers generally utilize higherwater flow rates. For instance, traditional pressure swirl atomizersinclude multiple inlet channels and are used to inject water upstream ofa turbine of a high performance jet engine to provide a temporary boostin thrust (because the water increases gas density across the turbine).In this case, high water flows can be delivered due to the high gasflows across the turbine. In the present application, to achieve lowwater flow rates suitable for the low gas flow rates utilized toventilate a patient, it has been discovered that a pressure swirlatomizer designed with a single inlet channel enables precise deliveryof highly atomized water at very low water flow rates. However, to theextent that adjusting the duration and/or interval of pulses deliveredto a hollow cone atomizer having more than one inlet channel can producelow water flow rates suitable for the present application, such a hollowcone atomizer can be implemented by the methods and systems herein tohumidify breathing gases.

The water may be pumped into the pressure swirl atomizer (e.g., 500 or600) at any suitable pressure, such as from 50 psi to 1500 psi. Thelower the pressure utilized, however, the slower the water flow ratethat exits the pressures swirl atomizer. The inlet channel 728 directsthe high-pressure water tangentially into the swirl chamber 522 (or722), resulting in a high velocity rotating fluid field in the swirlchamber 522 (or 722). The dimensions of the inlet channel 728 anddischarge orifice 520 (or 620) are minute. For example, the total inletarea of the inlet channel 728 may be 0.005 to 0.3 mm². In some aspects,the total inlet area of the inlet channel 728 is 0.008 mm² or 0.007 mm²,0.006 mm², 0.16 mm², or 0.18 mm². In other examples, the diameter of thedischarge orifice 520 (or 620) is from 0.4 to 2.0 mm. In some aspects,the diameter of the discharge orifice 520 (or 620) is 0.4 mm, 0.5 mm,0.6 mm, 0.7, 0.8 mm, 0.9 mm, or 1.0 mm. The dimensions of the dischargeorifice length/diameter ratio and swirl chamber diameter are also verysmall. For example, the discharge orifice length/diameter ratio may befrom 0.5 to 4.0. In some aspects, the discharge orifice length/diameterratio may be 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, or 1.4.For example, the swirl chamber diameter may be from 1.0 to 4.0 mm. Insome aspects, the swirl chamber diameter may be 1.5 mm, 1.4 mm, 1.3 mm,1.6 mm, 1.7 mm, or 1.8 mm. These dimensions are exemplary only and arenot meant to be limiting. Any suitable dimensions for providing a hollowcone spray with a thin wall of small water droplets may be utilized aswould be understood by a person of skill in the art.

Because this rotating field is at high pressure relative to ambient, avortex is created, causing the rapidly spinning water to be expelled outof the discharge orifice 520 (or 620) with high rotational velocity. Theresult is a “hollow cone” (e.g. 323 or 423) of very small waterdroplets. In some aspects the Sauter Mean Diameter (water droplet size)is from 1-100 microns. For example, the water droplet size may be 4, 5,or 6 microns. In further aspects, a cone wall thickness of the waterdroplet stream is from 0.01 to 0.8 mm. For example, the cone wallthickness may be in a range of 0.04 to 0.07 mm. In additional aspects, acone angle (the interior spread of the cone, shown in FIGS. 3 and 4) isgreater than 30 degrees. For example, the cone angle may be from 80degrees to 130 degrees. In some aspects, the pressure swirl atomizer 500(or 600) can produce cone angles of greater than 90 degrees, a cone wallor film thickness of less than 0.1 mm, and/or droplet sizes of less than10 microns. These characteristics of a high angle, very thin hollow cone323 (or 423) of very small water droplets differentiate a pressure swirlatomizer from other types of atomizers.

FIG. 8 is a partial, cross-sectional schematic diagram illustrating astand-alone humidifier 800 including a hollow cone atomizer 802 and agas flow sensor 805, in accordance with aspects of the disclosure.Humidifier 800 includes a heating tube 819 and is similar to humidifier300 in many respects. However, humidifier 300 does not include a gasflow sensor and is integrated into a ventilator, whereas humidifier 800includes an internal gas flow sensor 805 and is a stand-alone device.Humidifier 800 is also similar to humidifier 118, which is a stand-alonehumidifier installed outside of ventilator 100 near the inspiratory port125.

As illustrated, humidifier 800 is within a housing 827 and includeshollow cone atomizer 802 in a flow path 804 of a ventilator (similar toventilator 100 or ventilator 200, detailed above) during ventilation ofa patient 150, in accordance with aspects of the disclosure. Housing 827may be constructed of any suitable material for encasing the componentsand circuitry of the humidifier 800, which is further suitable forsterilization between patients. As with humidifier 118, humidifier 800comprises a heating tube 819 (similar to heating tube 119 and 319).While humidifier 800 is not shown in fluid communication with a heatinginspiratory limb (e.g., such as heating inspiratory limb 232), thisconfiguration is contemplated and humidifier 800 may easily beimplemented in such a system. In aspects, the hollow cone atomizer 802may be a pressure swirl atomizer. As illustrated, the hollow coneatomizer 802 is positioned to spray water directly into the flow path804 of breathing gases. As humidifier 800 is a stand-alone device, theflow path 804 is downstream from the pressure generating system 102 butupstream from the ventilator tubing system 130, as illustrated in FIGS.1 and 2.

As illustrated, humidifier 800 further includes computer circuitry 811,which includes a controller (such as controller 310 or controller 410),memory (such as memory 312 or memory 412), and at least one processor(such as processor 314 or processor 414). As detailed above, thecontroller of humidifier 800 may command a valve (not shown) to provide“bursts” of water (or water and medicine) to the hollow cone atomizer802. The duration and timing of bursts (as controlled by the opening andclosing of the valve) provides a prescribed amount of high-pressurewater to the hollow cone atomizer 802. These controlled bursts or pulsesallow the hollow cone atomizer 802 to deliver a specific amount ofatomized water (e.g., in a cone pattern of extremely small waterdroplets) to the gas stream, thereby preventing or reducing over orunder humidification.

As illustrated, the humidifier 800 also includes a temperature sensorand/or humidity sensor 807 located in flow path 804 upstream of thehollow cone atomizer 802. Humidifier 800 may also include a probe inlet829 for receiving temperature and/or humidity measurements at the wyefitting from a probe (such as probe 236). The temperature sensor and/orhumidity sensor 807 (and/or probe inlet 829) may be communicativelycoupled to humidifier 800 and may provide temperature and/or humiditymeasurements to the controller, which may then command the heating tube819 (and/or the heating circuit, not shown) to maintain a desiredtemperature and/or humidity of the breathing gases flowing through flowpath 804. Humidifier 800 further includes an internal gas flow sensor805, enabling the humidifier 800 to be a stand-alone device. Asillustrated, internal gas flow sensor 805 may be downstream oftemperature sensor and/or humidity sensor 807, and upstream of thehollow cone atomizer 802. The internal gas flow sensor 805 may provide agas flow signal to the controller for determining a desired amount ofwater to be delivered to the gas stream in flow path 804.

As illustrated, the humidifier 800 also includes a heating tube 819,which is similar to heating tube 119 and 319 described above. Theheating tube 819 includes a thermally-conductive material that issurrounded by or integrated with a heating element (not shown). Asdescribed above, a heating element may generate thermal energy via anysuitable means, e.g., electrical, chemical, or otherwise, and maydeliver the thermal energy to the thermally-conductive material via anysuitable means (e.g., via an external sleeve or blanket, internal orexternal wiring, etc.). As illustrated in FIG. 8, the heating tube 819is in fluid communication with outlet 813, which is in fluidcommunication with a heating or non-heating inspiratory limb of theventilation tubing system (not shown). As described above, the heatingtube 819 is positioned directly downstream of the hollow cone atomizer802, such that when a hollow cone of small droplets of water (or waterand medicine) from the hollow cone atomizer 802 contacts the heatedsurface of the heating tube 819, the small droplets of water arevaporized, turning into gaseous water vapor. This gaseous water vaporenters the stream of breathing gases in flow path 804, forming a gaseoussolution of humidified breathing gases.

The humidifier 800 further includes a display 815 and a push button 817.Display 815 may provide, for example, a user-selected humidity set point(e.g., between 50% and 99%), a user-selected temperature of humidifiedbreathing gases (e.g., within a range of 32 to 42 degrees C.), ameasured humidity of breathing gases (e.g., as measured at the wyefitting by a probe, or at another suitable location), a measuredtemperature of humidified breathing gases (e.g., as measured at the wyefitting by a probe, or at another suitable location), and alarms and/oralerts. Push button 817, which may alternatively be represented by oneor more controls of a touch-enabled graphical user interface (GUI)provided by display 815, enables selection of a humidity set point(e.g., between 50% and 99%), selection of a temperature for humidifiedbreathing gases (e.g., within a range of 32 to 42 degrees C.), andselection of alarm and/or alert thresholds.

FIG. 9 is an isometric view of a schematic diagram illustrating astand-alone humidifier 900 within a housing (such as housing 827,describe above), in accordance with aspects of the disclosure.Humidifier 900 is similar to humidifier 800, as described above. Asillustrated, humidifier 900 includes a display 915 (such as display 815,described above), a push button 917 (such as push button 817, describedabove), and a patient probe connector 933 (e.g., in communication withprobe inlet 829, described above). Humidifier 900 further includesinspiratory and expiratory heater connections 931 for powering and/orcontrolling heating elements associated with regulating a temperature ofa heating inspiratory limb (e.g., heating inspiratory limb 232) and/or aheating exhalation limb (e.g., heating exhalation limb 234).

FIGS. 10A-10D illustrate alternative spray patterns of hollow cone orfull cone atomizers, in accordance with aspects of the disclosure.

FIG. 10A illustrates a spray pattern of a hollow cone atomizer with anaxially-directed spray of small water droplets impinging on an insidediameter of a heated tube. In this case, a direction of the spray is inthe same direction as gas flow. Here, because the trajectory of thewater droplets does not oppose the momentum of the incoming gas flow,the effect of the gas flow causes minimal disturbance to the path of thewater droplets towards their target (i.e., the heated tube). In aspects,a full cone atomizer may also be used, but is less desirable becausefurther heating downstream of the atomizer may be required to fullyevaporate the injected water. Additionally, it may be difficult todeliver a low water flow with full cone atomizer.

FIG. 10B illustrates a spray pattern of a hollow cone or full coneatomizer with an axially-directed spray impinging on a plurality ofsmall heated metal conduits that are aligned axially with the gas flow.These conduits are formed of a thermally-conductive material, such as analuminum honeycomb or similar metal or alloy. In aspects, a heated tubemay be used in conjunction with the heated conduits. However, in thiscase, heating the conduits may not be controlled as precisely as aheating tube, causing vaporization effectiveness to be less certain.Furthermore, cleaning of the conduits may be more difficult than aheating tube. If a full cone atomizer is used, it may be difficult todeliver a low water flow.

FIG. 10C illustrates a spray pattern of a hollow cone or full coneatomizer with a perpendicularly-directed spray impinging on a portion ofthe inside diameter of a heating tube. Alternatively, theperpendicularly-directed spray may impinge on an alternatively-shapedheated surface, with or without an additional heating tube. In thisexample, vaporization effectiveness may be less certain and/or mayrequire a higher temperature due to the lower heated surface area. If afull cone atomizer is used, it may be difficult to deliver a low waterflow.

FIG. 10D illustrates a spray pattern of a hollow cone or full coneatomizer with an axially-directed spray impinging on an inside diameterof a heating tube. In this case, the spray is directed opposite (facing)a direction of the gas flow. In this case, by injecting into the face ofthe gas stream, more water droplets may be swept into the center of thegas flow stream and would not contact the heated tube surface. Here,vaporization effectiveness may be less certain and further heating maybe required downstream of the humidifier to ensure full vaporization. Ifa full cone atomizer is used, it may be difficult to deliver a low waterflow. Additional descriptions and interactions between the componentsshown in FIGS. 1-10D are provided in method 1100, as described belowand/or as illustrated in FIGS. 1-10D.

FIG. 11 is a flow diagram illustrating a method 1100 for humidifyingbreathing gases for delivery by a ventilator to a patient, in accordancewith aspects of the disclosure. Method 1100 reduces and/or prevents overor under humidification of breathing gases, where over humidificationcauses rainout in the patient circuit and under humidification causespatient airway dryness, airway injury, and/or discomfort. For example,method 1100 reduces and/or prevents over or under humidification byutilizing a hollow cone atomizer (e.g., a pressure swirl atomizer) todeliver a controlled amount of water to the breathing gases and/or bycontrolling a temperature of a heating element within a heating tube ofthe humidifier (and/or within a heating circuit) to maintain a desiredhumidity of the breathing gases. In addition to preventing or reducingover or under humidification, method 1100 can utilize less waterresulting in less exhalation filter saturation. Further, because method1100 utilizes a heating element adapted to quickly reach a desiredtemperature (e.g., in one minute or less), method 1100 requires minimalwarm up time. In some aspects, the use of a heating element to heat theexpiratory inspiratory limb by method 1100 can further prevent rainoutin the exhalation limb. In some aspects, method 1100 is performed by ahumidifier integrated with a ventilator. In other aspects, method 1100is performed by a stand-alone humidifier coupled to a ventilator.

As illustrated, method 1100 begins with receive operation 1102. Atreceive operation 1102, the humidifier receives inspiratory flowinformation about breathing gases upstream from an atomizer of thehumidifier from a ventilator and/or one or more flow sensors. In someaspects, the one or more flow sensors are part of the humidifier. Inother aspects, the one or more flow sensors are part of the ventilator.The inspiratory flow information may be a ventilator inspiratory flowcommand or a measured inspiratory flow rate.

At receive operation 1104, the humidifier receives humidity informationfrom at least one of the ventilator or one or more upstream humiditysensors. The humidity information may be relative humidity and/or atemperature of the breathing gases upstream of the atomizer of thehumidifier. For example, the breathing gases may be in a flow path of apressure generating system of a ventilator.

At calculate operation 1106, a processor of the humidifier calculates anamount of water to add to the breathing gases to reach a desiredhumidity based on the inspiratory flow information and/or the humidityinformation. In some aspects, the desired humidity may be auser-selected humidity set point (e.g., as a humidity percentage)between 50% and 99%. This range is exemplary only and is not meant to belimiting. Any desired humidity that is greater than the relativehumidity of the upstream breathing gases may be utilized. The humidifierduring calculate operation 1106 may utilize the inspiratory flowinformation and/or the humidity information (which humidity informationmay include a relative humidity as well as a temperature measurement ofthe upstream breathing gases) to determine an amount of water to add tothe breathing gases to reach the desired humidity. In some cases, atcalculate operation 1106, the processor of the humidifier may alsocalculate a temperature of a heating element for vaporizing the amountof water to be added to the breathing gases (or for maintaining thedesired humidity in the breathing gases).

At optional second calculate operation 1107, when the water includes adissolved medicine, a processor of the humidifier may calculate anamount of water including the dissolved medication. In this case, theamount of water may be calculated (above) to be sufficient to maintainthe user-selected relative humidity of the breathing gases. Based on theamount of water and the concentration of the medicine, a secondcalculation may determine an amount of medicine that will be deliveredto the breathing gases. As the amount of water may be required tomaintain the user-selected humidity, a concentration of the medicinewithin the water may be adjusted to ensure delivery of a prescribedamount of the medicine. In some cases, when the medicine is infused intothe water as it is pumped to the valve and/or atomizer, the infusionrate may automatically be adjusted based on the amount of watercalculated in operation 1106 above. Other methods of determining anddelivering an appropriate amount of medicine to the breathing gases mayalso be implemented, as known by one of skill in the art, and the aboveexample is not intended to be limiting.

At control operation 1108, the humidifier controls an atomizer (and/or avalve) to deliver the amount of water (or water and medicine) calculatedduring operation 1106 (and optionally at operation 1107) to thebreathing gases. In some aspects, at control operation 1108, thehumidifier controls a valve to deliver the calculated amount of water intimed bursts of water to the atomizer, which delivers the calculatedamount of water as small water droplets (e.g., in a hollow cone pattern)directly into the flow path of the breathing gases. For example theatomizer may be a hollow cone atomizer such as a pressure swirlatomizer. In some aspects, the valve may be a fast-response valve, suchas fast-response solenoid valve, so that the calculated amount of watercan be delivered in bursts or pulses to the atomizer. In furtheraspects, the humidifier during control operation 1108, controls thevalve to deliver the calculated amount of water to the atomizer byadjusting a number and duration of the pulses during a predetermineddelivery time.

In some aspects, a pump, such as a high pressure pump is fluidlyconnected between a water reservoir and the valve. In these aspects,upon opening of the valve, high pressure water is dispersed through thevalve to the atomizer. For example, the high pressure water may have psiof greater than 50, 100, 200, 250, 300, 350, or 400 psi. In someaspects, the solenoid valve may be eliminated by using a pump that has ameans of providing fast, well-timed, high pressure pulses of water tothe atomizer upon an electrical command.

In some aspects, the humidifier at control operation 1108 delivers thecalculated amount of water through a pressure swirl atomizer to thebreathing gases. In these aspects, pressurized water may be ported to asingle inlet channel in a distributor of the pressure swirl atomizer.The inlet channel directs the high-pressure water tangentially into aswirl chamber, resulting in a high velocity rotating fluid field in theswirl chamber. Because this rotating field is at high pressure relativeto ambient, a vortex is created, causing the rapidly spinning water tobe expelled out of the swirl chamber through a discharge orifice withhigh rotational velocity. The result is a spray of a “hollow cone” ofvery small water droplets. For example, the pressure swirl atomizer mayproduce cone angles (or average or mean cone angles) greater than 90 or100 degrees, a film of water droplets (or a cone wall thickness) lessthan 0.1 mm, and/or water droplet sizes in the hollow cone of less than10 microns. These characteristics of a high angle, very thin hollow coneof very small water droplets is what differentiates the pressure swirlatomizer from other types of atomizers.

At control operation 1110, the humidifier controls a heating element ata temperature (e.g., a temperature calculated at operation 1106) tovaporize the atomized water in the flow path downstream of the atomizerto form a humidified breathing gas. In some aspects, as described above,the heating element may be associated with a heating tube integrated inthe humidifier; in other aspects, the heating element may be associatedwith a heating circuit including a heating inspiratory limb (and, insome cases, a heating exhalation limb). In further aspects, a heatingelement may be utilized in both a heating tube of the humidifier and aheating circuit. In examples, when the atomized water contacts theheating element (or a thermally-conductive material associated with theheating element), the water droplets vaporize to form gaseous watervapor. The gaseous water vapor may then diffuse in the breathing gasesof the flow path to form a gaseous mixture of humidified breathinggases. In aspects, based on vaporizing the calculated amount of water,the humidified breathing gases are not over or under humidified andexhibit a desired humidity between 50% and 99% relative humidity (e.g.,based on a user selection).

At determination operation 1112, the humidifier may receive differenthumidity information about the humidified breathing gases from a probeassociated with a wye fitting of the ventilation tubing system. In thiscase, the different humidity information at the wye fitting may indicatethat the humidified breathing gases are not at the desired humidity. Ifthe humidifier receives different humidity information, the method mayprogress to recalculate operation 1114. If the humidifier does notreceive different humidity information, the method may return to controloperation 1108 and the humidifier may continue to deliver the calculatedamount of water into the flow path of the breathing gases.

At recalculate operation 1114, a processor of the humidifierrecalculates an amount of water to add to the breathing gases to reachthe desired humidity based on the different humidity information. Thehumidifier during recalculate operation 1114 may also utilize theinspiratory flow information to determine an adjusted amount of water toadd to the breathing gases to reach the desired humidity. In some cases,at calculate operation 1114, the processor of the humidifier may alsorecalculate a temperature of the heating element for vaporizing theadjusted amount of water to be added to the breathing gases (or foradjusting the temperature of the humidified breathing gases to reach thedesired humidity). For example, based on the different humidityinformation, the humidifier may also control a temperature of thehumidified breathing gases at the wye fitting to a user-selectable levelin a range of, for example, 32 to 42 degrees C. Upon recalculating theamount of water and/or the temperature of the heating element, themethod may return to control operation 1108 to vaporize the adjustedamount of water by controlling the heating element (which may also becontrolled to an adjusted temperature).

After the breathing gas has been humidified at control operation 1110,the humidified breathing gases at the desired humidity may be deliveredto the patient circuit for delivery to a patient being ventilated by theventilator. In this way, method 1100 prevents or reduces over or underhumidification of breathing gases.

In some aspects, a microprocessor-based ventilator or humidifier thataccesses a computer-readable medium having computer-executableinstructions for performing the method of humidifying ventilationbreathing gas is disclosed. This method includes repeatedly performingthe steps disclosed in method 1100 above and/or as illustrated in FIGS.1-10A.

Those skilled in the art will recognize that the methods and systems ofthe present disclosure may be implemented in many manners and as suchare not to be limited by the foregoing exemplary aspects and examples.In other words, functional elements being performed by a single ormultiple components, in various combinations of hardware and software orfirmware, and individual functions, can be distributed among softwareapplications at either the client or server level or both. In thisregard, any number of the features of the different aspects describedherein may be combined into single or multiple aspects, and alternateaspects having fewer than or more than all of the features hereindescribed are possible. Functionality may also be, in whole or in part,distributed among multiple components, in manners now known or to becomeknown. Thus, myriad software/hardware/firmware combinations are possiblein achieving the functions, features, interfaces and preferencesdescribed herein. Moreover, the scope of the present disclosure coversconventionally known manners for carrying out the described features andfunctions and interfaces, and those variations and modifications thatmay be made to the hardware or software firmware components describedherein as would be understood by those skilled in the art now andhereafter.

Numerous other changes may be made which will readily suggest themselvesto those skilled in the art and which are encompassed in the spirit ofthe disclosure and as defined in the appended claims. While variousaspects have been described for purposes of this disclosure, variouschanges and modifications may be made which are well within the scope ofthe present disclosure. Numerous other changes may be made which willreadily suggest themselves to those skilled in the art and which areencompassed in the spirit of the disclosure and as defined in theappended claims.

1-20. (canceled)
 21. A method for humidifying ventilator-deliveredbreathing gas, comprising: receiving, at a humidifier, inspiratory flowinformation about breathing gas flowing from a ventilator into thehumidifier; measuring, by the humidifier, humidity information for thebreathing gas; calculating, based on the inspiratory flow informationand the humidity information, an amount of water to add to the breathinggas to reach a desired humidity; delivering, by humidifier, thecalculated amount of water in bursts of water directly into a flow pathof the breathing gas; vaporizing the bursts of water upon contact of thewater with a heating surface in the flow path to form humidifiedbreathing gas; and delivering the humidified breathing gas to aventilation tubing system for delivery to a patient.
 22. The method ofclaim 21, wherein the heating surface comprises a thermally-conductivematerial in thermal contact with a heating element.
 23. The method ofclaim 21, wherein the bursts of water are delivered by a hollow coneatomizer.
 24. The method of claim 23, wherein the bursts of watercomprise water droplets having a Sauter Mean Diameter of 6 microns orless.
 25. The method of claim 21, wherein the inspiratory flowinformation is received from the ventilator and comprises a flow rate ofthe breathing gas.
 26. The method of claim 21, wherein delivering thebursts of water comprises spraying water in a pattern of water droplets.27. The method of claim 21, wherein inspiratory flow information ismeasured by a sensor of the humidifier.
 28. The method of claim 21,wherein the water is delivered at a pressure of at least 50 pounds persquare inch (PSI).
 29. The method of claim 21, further comprising:receiving wye humidity information; and adjusting at least one of theamount of water to add to the breathing gas or a temperature of theheating surface to reach the desired humidity.
 30. The method of claim21, further comprising: receiving, at the humidifier, a temperaturemeasurement of the breathing gas flowing into the humidifier; andwherein calculating the amount of water is further based on thetemperature measurement.
 31. The method of claim 21, wherein the amountof water comprises a dissolved medicine.
 32. The method of claim 21,wherein the humidity information includes a temperature measurement anda relative humidity of the breathing gas flowing into the humidifier.33. A humidifier that provides humidification to breathing gas forventilating a patient, comprising: a first sensor that monitors aninspiratory flow of breathing gas flowing into the humidifier from aventilator; a second sensor that monitors humidity information of thebreathing gas flowing into the humidifier; a processor that calculates,based on the inspiratory flow and the humidity information, an amount ofwater to add to the breathing gas to reach a desired humidity; and acontroller that commands: injection of the amount of water in bursts ofatomized water directly into a flow path of the breathing gas; andheating of a heating element to heat a thermally-conductive material inthe flow path downstream of an injection point of the injected water,wherein the injected water is vaporized upon contact of the water withthe thermally-conductive material to form humidified breathing gas fordelivery to a patient being ventilated by the ventilator.
 34. Thehumidifier of claim 33, wherein the heating element is associated with aheating tube comprising the thermally-conductive material.
 35. Thehumidifier of claim 33, wherein the heating element is associated with aheating circuit comprising the thermally-conductive material, andwherein the heating circuit is located downstream of the humidifier. 36.The humidifier of claim 35, wherein the heating circuit comprises aheating inspiratory limb.
 37. The humidifier of claim 35, wherein theheating circuit comprises a heating inspiratory limb and a heatingexhalation limb.
 38. The humidifier of claim 33, wherein the firstsensor is downstream from the second sensor.
 39. A humidifier thatprovides humidification to breathing gas for ventilating a patient,comprising: a sensor that monitors humidity information of the breathinggas flowing into the humidifier; a controller that receives aninspiratory flow of the breathing gas flowing into the humidifier; aprocessor that calculates, based on the inspiratory flow and thehumidity information, an amount of water to add to the breathing gas toreach a desired humidity; a valve commanded by the controller to causedelivery of the amount of water in bursts of water directly into a flowpath of the breathing gas; and a heating element commanded by thecontroller to heat a thermally-conductive material, wherein the burstsof water are vaporized upon contact of the water with thethermally-conductive material to form humidified breathing gas fordelivery to a patient being ventilated by the ventilator.
 40. Thehumidifier of claim 39, wherein the heating element includes a pluralityof metal conduits that are axially aligned with the flow path of thebreathing gas.